1. Field of the Invention
The present invention is directed to a controller for editing encoded image data in an electrographic printer or copier device.
2. Description of the Related Art
The editing ensues such that a character generator can generate a charge image on an intermediate carrier that is dependent on the image data. The encoded image data are transferred from a host or some other data processing system to the controller, as disclosed, for example, by U.S. Pat. No. 5,012,434, in the form of commands of a specific, standardized language. For example, PCL (Printer Control Language) of Hewlett Packard and IPDS (Intelligent Printer Data Stream) of IBM are such languages. The commands contain all data for constructing a page to be printed. In particular, these are positioning information for positioning characters and images on a page, information from which the font of individual characters are to be taken, link information to other masters such as, for example, forms, and the pixel data for specific images to be printed. With the assistance of the controller, the received image data are converted into pixels that are arranged matrix-like such that the image data can be forwarded row-by-row or column-by-column to a following character generator.
U.S. Pat. No. 5,157,765 discloses a method and an apparatus for editing an encoded image data stream into a pixel data stream for driving a printer. A division of the rastering work for editing a page onto a plurality of processors is proposed in order to save memory space and in order to use the available processor capacity with high efficiency. In a four-stage process, independent blocks of a page to be printed are first identified and stored. In the second step, the blocks are converted into objects and data accesses to frequently employed resources such as, for example, characters are organized. In the following process, the positions of the objects on the page to be edited are determined. In the last stage, the objects are rastered and edited into a rastered, full page.
An electrographic printer or copier device that contains an optical or magnetic character generator is disclosed, for example, by European Patent Document EP-0 403 476 B1. Both a character generator that deflects a laser beam as well as a character generator working with LED lines is thereby suitable as an optical character generator. Print data that is present in pixel form are converted with a character generator into an optical or magnetic image with which a photoconductive or, respectively, ferromagnetic layer of a continuously revolving charge storage drum or of a corresponding band-shaped intermediate carrier of the printer or copier device is exposed in order to generate a latent charge or, respectively, a magnetic field image. This image is developed in a known way and transfer-printed onto a recording medium.
A controller must exhibit a corresponding calculating and raster capacity that is dependent on the performance capability of the printer or copier device in which it is utilized. In standard fast printer and copier devices, 50 to 350 DIN A4 pages are printed per minute. Dependent on the specific performance of a printer, one is compelled to either utilize specific controllers for the respective printer or, on the other hand, to accept an over-dimensioning of the controller. The raster capacity is limited by the access times onto the memory and the calculating capacity is limited by the performance of the processor employed.